4 A factory estimates that 0.25% of its production of small components is defective. These are sold in packets of 200. Calculate the percentage of the packets containing one or more defectives. The...

4 A factory estimates that 0.25% of its production of small components is defective. These are sold in packets of 200. Calculate the percentage of the packets containing one or more defectives.

The average number of faults in a metre of cloth produced by a particular machine is 0.1. (a) What is the probability that a length of four metres is free from faults? (b) How long would a piece have to be before the probability that it contains no flaws is less than 0.95?